Conventionally, a configuration such as, for example, the one disclosed in Patent 1 below is known as this type of vibration-damping device. The vibration-damping device shown in Patent 1 below includes a tubular first mounting member connected to one of a vibration-generating part and a vibration-receiving part, a second mounting member connected to the other one thereof, an elastic body which elastically connects the first mounting member and the second mounting member, and a partitioning member which partitions a fluid chamber in the first mounting member which is filled with fluid into a main fluid chamber on one side having the elastic body as one part of its wall face and an auxiliary fluid chamber on another side. In this vibration-damping device, the partitioning member is provided with a limiting passage and a switching means. The limiting passage connects the main fluid chamber and the auxiliary chamber, and generates fluid column resonance when fluid flows in it. The partitioning member includes a plurality of limiting passages with mutually different resonance frequencies. The switching means switches the limiting passage in which the fluid flows.
For example, high-frequency idle vibration and low-frequency shake vibration are input to this type of vibration-damping device. To reliably damp and absorb these multiple types of vibrations in mutually different frequency bands, it is preferable to highly precisely switch the limiting passages in which the fluid flows according to the frequency of the input vibration, such that fluid column resonance is generated in the limiting passage at a resonance frequency which corresponds to the input vibration.
Since the amplitude of shake vibration is greater than the amplitude of idle vibration, when shake vibration is input, there is a large fluid pressure fluctuation (fluid pressure amplitude) in the main fluid chamber. Accordingly, in the conventional vibration-damping device, the switching means switches the limiting passages in which the fluid flows according to the fluid pressure fluctuation in the main fluid chamber. This makes it possible to switch the limiting passage that the fluid flows along when shake vibrations which have a lower frequency than idle vibration is input.